AND CHEMISTRY OF HOPS. 9 



&c., in summer, as its leaves are very large and afford a fine 

 shade. The " white bine " and the " grey bine " are the best 

 sorts for this purpose ; they succeed each other. 



The flower, forming a spiked inflorescence, gives rise to 

 scales, at the base of which the fruit is developed, protected 

 against humidity by the resinous and very odoriferous powder 

 of a golden yellow, named lupuline. 



In a technical point of view, hops are the principal 

 element in the brewing industry ; but being very sensible 

 to the action of air, they easily deteriorate, in spite of the 

 generally practised compression ; the essential oil which they 

 contain becomes rancid and engenders a mouldiness, so that 

 they do not keep longer than a year. To overcome this diffi- 

 culty, and in order to give a more presentable aspect to his 

 merchandise, the hop merchant has recourse to sulphuring, 

 an operation always successful, but which at the same time 

 produces a pernicious reaction on the essential oil, which 

 thereby undergoes a chemical conversion. Under the action 

 of the sulphurous acid, which passes over the hops, the essen- 

 tial oil is oxidized, converted into valerianic acid, and com- 

 bines with the sulphur to form a solid body. In this manner 

 the oily matter of the hops is destroyed and the mouldiness 

 prevented ; but beer manufactured with sulphured hops will 

 never be a wholesome beverage. The aroma of the hops is 

 replaced by that of the valerianic acid, the sulphurous acid 

 contained in the hops is partly converted into sulphuric 

 acid, and the sulphur of commerce being arseniferous, the 

 arsenious acid passes with the sulphurous acid in the hops, 

 both are communicated to the beer, and may, although taken 

 in small doses, inconvenience the consumer, 



